Harold e



H. E. YARHUW.

TURBINE BLADE. APPLICATION FILED JUNE 5. 19%8.

Patented Aug. 12, 1919.

HAROLD E. YABROW, OF GLASGOW, SCOTLAND.

TURBINE-BLADE.

Specification of Letters Patent. Patented Aug. 12, 1919;

Application filed June 5, 1913. Serial No. 238,347.

To all whom it may concern:

Be it known that I, HAROLD EDGAR YA R- now, a subject of the King ofGreat Britain, residing in Glasgow, Scotland, have invented certain newand useful Improvements Relating to Turbine-Blades, of which thefollowing is a specification.

The invention relates to the blades of turbines and more particularly tothe form given to the edges of the blades.

It is found that the'blades are crack, especially at the roots of theblades, and this drawback has been accentuated, particularly in marinepractice, by the employment of material suited to the use of superheatedsteam.

The edges of the turbine blades are generally sharp in orderto lessenthe losses due to eddy currents, but a sharp edge is not suitable forwithstanding stresses, especially variable bending stresses, such asoccur in a turbine, since it is well known that slight hair cracks arevery liable to be formed in edges and sharpcorners. and, when onceformed, extend more deeply.

According to the invention this drawback is obviated by rounding theedges of the blades for a small portion of their length at the endprojecting from the drum or casing to which the shank of the blade issecured. As this rounded portion is confined to a short length of theblade and the rest of the edges of the blade is quite sharp, noappreciable loss is incurred by the eddies.

liable to The accompanying drawing shows an example of the improvementaccording to the invention, in which Figure 1 is asectionof a blade asusually fitted showing at A the sharp edges of the blade. Fig. 2 showsat B 5 those edges rounded off at the part where the blade is secured tothe drum or casing.

Figs. 3 and 4 are two elevations at right angles of the blade.

As shown more particularly in Fig. 4:, the rounding may terminate in acomparatively sharp curve, as shown by the full lines at C,

and by a long taper, as shown by the broken me. from 10 to 25 per cent.ofthe total length of the blade. 7

Having now described the nature of the said invention and the best meansI know of citrrying the same into practical effect, I 0 aim Y A turbineblade, the edges of whichare.

rounded for a short portion of their length at the end projecting fromthe drum or cats ing to which the shank of the blade is secured.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

HAROLD E. YARBOW.

Witnesses:

JAMES. RITCHIE, J. W. BLAcK;

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, 1).,0. r

The rounded portion C D may be

